Get the time at which the data was cached. Note that keys expire in memcache, which means that it's possible that the date will disappear before the data – in this case we'll have to assume the data is still good.

Set the entire contents of the cache. WARNING: THIS DOES NOT FLUSH THE CACHE FIRST! This is because there is no "scope restriction" for flushing within memcache and therefore a flush here would flush the entire cache, resulting in more subsequent calls to this function, resulting in more flushes, etc.